Portable power supply devices, such as batteries are widely used as power sources in portable electrical and electronic products. Recently, Lithium Batteries have become attractive devices for providing portable power due their generally high power to weight ratio, and in the case of rechargeable configurations, their durability in maintaining high functionality after repeated charge and discharge.
Lithium batteries as a term typically refers to a family of batteries with different chemistries, comprising may types of cathode and electrolytes, but for general purposes they can be separated into two categories. Lithium metal batteries are generally non-rechargeable and have lithium metal or lithium compounds as an anode. As lithium metal batteries are not rechargeable they are also referred to as primary batteries. Lithium metal batteries are typically used to power devices such as watches, camera, calculators, scales, sensors, and the like.
Lithium-ion batteries which may also be identified as Li-ion batteries, are a type of rechargeable battery. As they are rechargeable they are also referred to as secondary batteries. Li-ion batteries are typically used to power mobile telephones, smart phones, laptops, medical devices, industrial equipment, automobiles and the like.
There is a specific difference between a battery and a cell as indicated by the UN Manual of Tests and Criteria. Specifically, a “battery” is understood to be two or more cells which are electrically connected together and fitted with devices necessary for use, such as a case, terminals, labels, protective devices, and the like. A “cell” is a single encased electrochemical unit having one positive and one negative electrode which exhibits a voltage differential across its two terminals. Many items called lithium batteries that are in fact a single cell, are in fact considered a cell for testing and transportation purposes.
While the rate of failures associated with the use of lithium based batteries is small especially in comparison to the large number of Li-ion batteries in use worldwide, several incidents have been well publicized and have raised awareness that lithium batteries, understood as devices comprising multiple interconnected cells, can develop issues. In particular, Li-Ion batteries when in use or when shorted accidently may develop significant heat, which can lead to explosion and or fire.
Although many forms of transpiration exist—car, truck, train, boat, or the like—aircraft transportation has become very common Though rare, problematic Li-ion batteries generating heat leading to fire and or explosion are highly undesirable conditions to experience while in flight. As such there has been a growing desire to establish rules and regulations for the transpiration of electrochemical power devices such as lithium based batteries. These rules and regulations generally pertain to additional testing measure for the batteries themselves, increased housing and shipping structures and of course overall cost for both the certification and shipping measures.
Specifically, the International Air Transport Association has issued a specific guideline for lithium battery transport based on the findings of the ICAO Dangerous Goods Panel (DGP) in 2012 which may be summarized to state that lithium batteries over 100 watt hours or lithium cells over 20 watt hours are now to be declared Class 9 Hazardous Goods when shipping. As a consequence, lithium batteries over 100 watt hours or lithium cells over 20 watt hours require special training and licenses to ship. They also require UN/DOT 38.3 testing prior to shipping and certification. Moreover, despite a growing need for portable lithium batteries with over 100 watt hours or lithium cells each with over 20 watt hours, the costs and the time associated with transporting such portable power devices, especially by air, are substantially increasing.
Although one or more individual cells are not considered to present the same potential problems and issues, individual cells are inconvenient. Portable high power communication systems, computers, medical devices, and most other high power portable systems are designed with the expectation that a battery composed of multiple cells will be available for use in the desired location. In many instances, these multiple cell batteries can be quite large which places the desire for portable power by way of a lithium based battery at odds with the new and developing rules and regulations for commercial transportation of the battery systems.
Hence there is a need for a method and system that is capable of overcoming one or more of the above identified challenges.